title: Assessment of left ventricular regional wall motion and ejection fraction with low-radiation dose helical dual-source CT: comparison to two-dimensional echocardiography.
abstract: BACKGROUND
  Electrocardiographic (ECG)-based tube current modulation during cardiac CT reduces radiation exposure but significantly increases noise in parts of the cardiac cycle where tube current is minimized.
  
  
  OBJECTIVE
  We evaluated the effect of maximal ECG-based tube current reduction on left ventricular (LV) regional wall motion assessment and ejection fraction (EF) by comparing low-radiation helical dual-source CT (DSCT) to 2-dimensional transthoracic echocardiography (2D-TTE).
  
  
  METHODS
  We studied 83 consecutive patients (15 with prior myocardial infarction) who underwent helically acquired DSCT coronary angiography with maximal ECG-based tube current modulation (low-radiation helical DSCT) and 2D-TTE within a 6-month period (median, 1 day), without any change in clinical status between the studies. In all patients, full tube current was applied only at 70% of the R-R interval, with minimal tube current (4% of maximum) in all other parts of the cardiac cycle. Reduced tube voltage (100 kVp) was combined with the maximal dose modulation in 34 patients. DSCT datasets were evaluated by a blinded, experienced cardiologist. Regional wall motion was assessed with the standard 17-segment model, with each segment scored as normal, hypokinetic, akinetic, and dyskinetic.
  
  
  RESULTS
  Mean effective radiation dose for the low-radiation helical DSCT was 5.2 ± 1.7 mSv. Regional wall motion was evaluable in all segments on low-radiation helical DSCT. There was excellent agreement of wall motion scoring by low-radiation helical DSCT and 2D-TTE in 1382 of 1411 segments (98%; Cohen's κ value 0.83; 95% confidence interval, 0.76-0.89; P < 0.0001). Mean LVEF was 67.6% ± 10.3% on low-radiation helical DSCT and 61.8% ± 10.3% on 2D-TTE (P < 0.0001).
  
  
  CONCLUSIONS
  Low-radiation dose helical coronary CT angiography with maximal ECG-based tube current modulation is comparable to 2D-TTE for regional wall motion and EF assessment.
authors.affiliation: Department of Imaging (Division of Nuclear Medicine), Cedars-Sinai Heart Institute, Cedars-Sinai Medical Center, 8700 Beverly Boulevard, Los Angeles, CA 90048, USA.
authors.forename: Ryo
authors.initials: R
authors.lastname: Nakazato
authors.forename: Balaji K
authors.initials: BK
authors.lastname: Tamarappoo
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Smith
authors.forename: Victor Y
authors.initials: VY
authors.lastname: Cheng
authors.forename: Damini
authors.initials: D
authors.lastname: Dey
authors.forename: Haim
authors.initials: H
authors.lastname: Shmilovich
authors.forename: Ariel
authors.initials: A
authors.lastname: Gutstein
authors.forename: Swaminatha
authors.initials: S
authors.lastname: Gurudevan
authors.forename: Sean W
authors.initials: SW
authors.lastname: Hayes
authors.forename: Louise E J
authors.initials: LE
authors.lastname: Thomson
authors.forename: John D
authors.initials: JD
authors.lastname: Friedman
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Berman
mesh_terms: D000328:Adult; D000368:Aged; D002140:California; D055424:Cardiac-Gated Imaging Techniques; D017023:Coronary Angiography / Q000379:methods*; D004562:Electrocardiography; D005260:Female; D006352:Heart Ventricles / Q000000981:diagnostic imaging; D006801:Humans; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction; D015588:Observer Variation; D011237:Predictive Value of Tests; D011829:Radiation Dosage; D011857:Radiographic Image Interpretation, Computer-Assisted; D015203:Reproducibility of Results; D012189:Retrospective Studies; D013318:Stroke Volume; D036542:Tomography, Spiral Computed; D014463:Ultrasonography; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging* / Q000503:physiopathology; D016277:Ventricular Function, Left